1. Field of the Invention
The present invention relates to improved tibial and femoral instrumentation method and apparatus for use in knee surgery and utilizing a plurality of reamers, each having a different cutting diameter to prepare a bore for the stem of a knee prosthesis and wherein the instrumentation registers upon a selected of the reamers that is of sufficient diameter to meet resistance in the patient's cortical bone. Even more particularly, the present invention relates to a system of knee surgery instrumentation that allows a surgeon to custom fit a knee prosthesis having a stem to a particular patient wherein the surgeon initiates a reaming of the intramedullary canal using a smallest cutting diameter reamer selected from a set of reamers, and progresses up in selected cutting diameters of the reamers until one of the reamers gets fixed or stuck in the patient's intramedullary canal, meeting resistance from cortical bone cutting or resecting instrumentation then registers upon the selected reamer after it cuts the cortical bone to prepare a bore for the prosthesis stem. All resectioning of the knee joint can be referenced to the reamer that is left in position when reaming is complete. The stem component of a knee prosthesis will closely fit the bore formed by the reamer. Instrumentation includes a cutting block oriented on the reamer, and all cuts made by the surgeon will be oriented relative to the stem or spike component of the prosthesis.
2. General Background
Often a knee prosthesis must be replaced, referred to as a revision case. In revision surgery, the existing component is removed from the tibia or femur. If cement was the means of attachment, it is cleaned and removed. The tibia or femur must then be recut.
Various devices have been patented which relate to the resectioning and preparation of the tibia or femur for prosthetic devices. In U.S. Pat. No. 4,474,177, entitled "Method and Apparatus For Shaping A Distal Femoral Surface", there is disclosed a method and apparatus for resectioning of the distal femur. An intramedullary reamer is used to internally locate the central longitudinal axis of the femur. The reamer is then removed and an intramedullary alignment guide is inserted in its place. The alignment guide has a handle attached to a rod portion at a preselected angle. Femoral surface modifying instruments can then be fixed to the guide handle and thus assume proper alignment with respect to the central longitudinal axis of the femur.
In U.S. Pat. No. 4,567,885, entitled "Triplanar Knee Resection System", there is provided a system for preparing a knee joint for a prosthesis. The triplanar system includes a guide member which has three pairs of parallel slots. The system further includes an intramedullary guide rod which is inserted into the femur. The guide rod has a 90.degree. bend. The guide member is affixed to the guide rod, the guide rod being used as an alignment means for the guide member. This patent is a divisional of U.S. Pat. No. 4,487,203, issued Dec. 11, 1984.
U.S. Pat. No. 4,722,330, entitled "Femoral Surface Shaping Guide For Knee Implants", discloses a distal femoral surface shaping guide for mounting on an intramedullary alignment guide. The main body of the shaping guide preferably contains at least one shaping guide surface. It may have an attachment for other shaping guides, however, preferably the main body of the shaping guide has integrally formed shaping guide surfaces.
U.S. Pat. No. 4,791,919, entitled "Surgical Instruments", discloses a set of femoral instruments which includes a femoral intramedullary alignment rod which may be introduced into the medulla by an alignment rod introducer. An angle adaptor which slides over the alignment rod forms a basis for the preparation of the femur using saw guides to receive the femoral component of the knee prosthesis.
U.S. Pat. No. 4,703,751, entitled "Method And Apparatus For Resecting A Distal Femoral Surface". The '751 patent discloses a method and apparatus for resecting a distal femoral surface. The apparatus includes an intramedullary rod, a jig which attaches to the rod, a cutting plate and a reference bar. The method and apparatus disclosed are for forming the initial resection along the transverse axis.
U.S. Pat. No. 4,738,254, entitled "Positioner For Surgical Instruments", discloses a positioner for surgical instruments used to invade a bone. The positioner comprises a body means, an alignment plate, and an alignment rod. The body has at least one guide surface for positioning a resectioning surgical instrument. The alignment rod which extends into the femoral shaft is used to locate the main body of the femoral resection guide in the correct position.
In U.S. Pat. No. 4,759,350, there is disclosed an apparatus and system for preparing distal femur and proximal tibia ends to receive a knee prosthesis. An intramedullary alignment guide is used to reference a femoral alignment guide for attachment across the distal femur after the distal femur cut has been made. The femoral alignment guide is in turn a reference for several cutting guides.
U.S. Pat. No. 4,907,578, discloses a distal femoral resector for resecting the distal femur. The resector comprises a T-shaped base with a rotating rod mounted through the base and an intramedullary alignment rod. The resector has a guide slot for guiding a cutting tool.
In U.S. Pat. No. 4,935,023, there is disclosed a distal femoral surface shaping guide which is mounted on an intramedullary alignment rod. The apparatus and method disclosed are particularly suitable for shaping one condyle for attachment of a unicondylar prosthesis.